Colleen Mouw calls herself an oceanographer "with one foot in the ocean and the other in the Great Lakes." An assistant professor in Michigan Technological University's Department of Geological and Mining Engineering and ...

Tropical Cyclone Fobane was located southeast of Reunion Island in the southwest Indian Ocean when the TRMM satellite passed over and captured rainfall and cloud data on the storm. TRMM saw that despite Fobane weakening, ...

The Tropical Rainfall Measuring Mission or TRMM satellite that observed the tropical low pressure area designated as System 91S earlier this week captured another look at a much weaker storm on January 30. Wind shear has ...

NASA's Aqua satellite passed over Tropical Cyclone Dylan and captured both visible and infrared imagery of the storm as it began landfalling. The visible image showed the extent of the storm, while the infrared data looked ...

It takes a lot of land to grow food for the world's seven billion people. About a third of Earth's terrestrial surface is used for agriculture. And about a third of that, in turn, is used to grow crops. Now, a new NASA-funded ...

The TRMM satellite flew above a System 91S, a tropical low pressure area, in the Mozambique Channel on January 28, 2014 at 1011 UTC/5:11 a.m. EST. TRMM data collected with this pass may be helpful in evaluating this low for ...

NASA's Aqua satellite passed over the tropical low pressure area designated as System 99P and infrared data shows that the low is getting organized. Meanwhile, the Australian Bureau of Meteorology posted a Cyclone Watch for ...

Satellite Data System

The Satellite Data System (SDS) is a system of United States military communications satellites. At least three generations have been used: SDS-1 from 1976 to 1987; SDS-2 from 1989 to 1996; SDS-3 from 1998 to the present. SDS satellites have a highly elliptical orbit, going from about 300 kilometers at perigee to roughly 39,000 km at apogee in order to allow communications with polar stations that cannot contact geosynchronous satellites. The high apogee meant that the polar regions were visible for long amounts of time, and only two satellites were required in order to achieve constant communications ability. The SDS satellites were constructed by Hughes Aircraft.

The primary purpose of the SDS satellites is to relay imagery from low-flying reconnaissance satellites to ground stations in the United States.

Each SDS-1 satellite had 12 channels available for ultra-high frequency communication. They were cylindrical in shape, roughly 25 feet (7.6 m) long. 980 watts of electrical power were available from solar panels and batteries. The SDS-1 had a mass of 1385 pounds (630 kilograms) and was launched on Titan-3B rockets. The SDS-1 satellites had similar orbits to the Air Force's Jumpseat ELINT satellites.

The SDS-2 is significantly more massive at 5150 pounds (2335 kg), with three separate communication dishes, including one for a K band downlink. Two dishes are 15 feet (4.5 meters) in diameter, while the third is 6.6 feet (2 m) in diameter. The solar arrays generate 1238 watts of power. It is believed that the Space Shuttle has been used to launch several satellites, possibly on missions STS-28, STS-38, and STS-53. Other launches have used the Titan-4 rocket.

Quasar is the rumored code name for the communications satellite.

A recent Quasar may have been launched into a high-apogee orbit from Cape Canaveral on August 31, 2004 by an Atlas 2AS rocket.